This application is based on Japanese Patent Application No. 2002-171094 filed on Jun. 12, 2002, the disclosure of which is incorporated herein by reference.
The present invention relates to a hybrid compressor apparatus and a method for controlling the hybrid compressor apparatus. The hybrid compressor apparatus is suitably used for an air conditioning system having a compression refrigerant cycle, which is mounted on a vehicle having idle stop function or on a hybrid vehicle.
Recently, in order to reduce a fuel consumption of an automotive vehicle, an automotive vehicle having idle stop function and a hybrid automotive vehicle are used. These vehicles are required to stop their engines in accordance with driving conditions. For example, in a vehicle having the idle stop function, an engine is required to stop when the vehicle stops temporarily, for example, at traffic lights. In a hybrid vehicle, an engine is required to stop when the vehicle stops temporarily, when the vehicle starts, and when the vehicle drives at a low speed. However, a compressor in an air conditioning system, which is driven by an engine in general, is required for operating, even when the engine stops.
In a hybrid compressor described in JP-A-2000-130323, an electromagnetic clutch connects between a pulley of an engine and the compressor, and a rotation shaft of the compressor disposed on an opposite side of the pulley connects to a motor. When the engine stops, the clutch disconnects between the pulley and the compressor, and the motor drives the compressor so that an air conditioning system is operated. In the above hybrid compressor, the motor needs to generate a large torque for driving the compressor. However, the size of the motor is limited because of its mounting performance and its manufacturing cost. Therefore, when the air conditioning system is required to operate under high cooling load such as during the daytime in high summer, the compressor is driven by the engine instead of the motor because the motor does not generate enough torque to drive the compressor. Thus, the idle stop function does not work efficiently for reducing a fuel consumption of the vehicle.
In view of the above problem, it is an object of the present invention to provide a hybrid compressor apparatus for a refrigerant cycle in the vehicle with an engine that is required to stop in accordance with driving conditions of the vehicle. This hybrid compressor apparatus effectively improves fuel consumption efficiency in the vehicle.
The hybrid compressor apparatus includes a motor, a compressor driven by at least one of the engine and the motor so as to compress refrigerant in the refrigerant cycle, a controller for controlling operation of the motor and the compressor and for selecting a driving source between the engine and the motor so as to drive the compressor, and a switch manually operated by a passenger of a passenger compartment so that the refrigerant cycle is operated in a normal mode or in an economy mode. In the hybrid compressor apparatus, when the economy mode is set while the engine stops, the motor drives the compressor. Therefore, a fuel consumption efficiency of the vehicle can be improved. Although a generating torque of the motor is limited, an operation load of the compressor can be reduced in a case of the economy mode, which is selected by the passenger. Thus, in the economy mode, the engine stops, and the compressor is operated only by the motor as much as possible, so that a fuel consumption of the vehicle can be reduced.
Preferably, the controller has a detecting unit for detecting an actual temperature at a predetermined position of the passenger compartment, and a determining means for determining a target temperature based on at least one of a setting temperature set by the passenger and the environmental conditions of the vehicle. In the economy mode while the engine stops, the motor drives the compressor even when the actual temperature is higher than the target temperature. More preferably, in the economy mode, the controller can change the target temperature to a modified target temperature, which is higher than the target temperature by a predetermined amount. Therefore, the load of the compressor can be effectively reduced.
Further, it is preferable that the controller has a determining means for determining an acceptable temperature that is an upper limit temperature, when the compressor is driven by the motor in the economy mode. In this case, when the actual temperature exceeds the acceptable temperature in the economy mode, the controller requests the engine to start and the motor to stop so that the compressor is driven by the engine. Therefore, air-conditioning feeling given to the passenger can be improved, while the fuel consumption efficiency can be improved.